This invention relates in general to a laminated belt and more specifically to a belt having a laminated strip over a seam and processes for fabricating and using the laminated belt.
Various techniques have been devised for joining belts such as photoreceptor belts. Belts may be joined in manufacture by overlapping the edge of one end of a sheet over the other opposite edge of the sheet thus forming a lap joint or seamed region that is thereafter welded. The technique of joining thermoplastic belted materials is well known and illustrated, for example, in U.S. Pat. No. 4,838,964 and U.S. Pat. No. 4,959,109, both of these patents being incorporated by reference herein in their entirety.
Acceptable joints formed in the aforementioned joining process for belt shaped electrophotographic imaging members perform satisfactorily when transported around relatively large diameter rollers. The lap joints or seams of these belts contain a deposit of web material melted during joining. These deposits or "weld splashes" are formed on each side of the welded web adjacent to and adhering to each end of the original web and to the regions of the web underlying each splash. Unfortunately, when the belts are transported around very small diameter rollers having, for example a diameter of about 19 mm or less, the weld splash on the outer surface of the belt gradually separates from the upper end of the photoreceptor web during cycling to form an open crevasse or crack which is repeatedly struck by conventional cleaning blades during image cycling to cause the weld splash on the outer surface of the belt to also separate from the underlying web so that it is held to the belt at a small linear region located along the length of the splash on the side of the splash opposite the upper end of the photoreceptor web. This small linear region located along the length of the splash on the side of the splash opposite the upper end of the photoreceptor web functions as a hinge that allows the weld splash to pivot or flop away from the upper end of the photoreceptor web and from the underlying web so that carrier beads and toner particles or liquid ink developer collected in the space between the web and splash are periodically ejected when the splash flops open and closed when the seam passes the cleaning blade and also when it travels around small diameter rollers. The ejected materials float to various subassemblies (e.g. corotrons, lamps) and causes them to fail or perform poorly and ultimately cause copy defects. It is also believed that due to the roughness of the welded seam, the response time of the cleaning blade is not fast enough to conform to each hill and valley of the seam. This also provides an opportunity for the fibers to be trapped under the blade. Collisions of the blade with the flopping splash also result in the blade becoming chipped and pitted. These chips and pits in the blade leave streaks of toner or liquid ink on the photoreceptor surface which eventually appear as streaks on copies made during subsequent electrophotographic imaging cycles and adversely affect image quality.
In the non-welded regions of the photoreceptor, deposited electrostatic charges may be dissipated when exposed to an erase light. However, in welded regions of the photoreceptor, the continuity of the layers is disrupted by the welding process so that complete discharge of the welded region is not possible. Thus, when the charged portions of the welded seam pass through the development zone, toner is deposited and this deposited toner is at least partially removed during the cleaning operation. Unfortunately, the removed toner does not contribute to the forming of toner images on final copies and greatly increases the overall toner consumption of the imaging device. This problem is particularly acute in modular cartridge-type systems in which most of the functional components of a copier, including toner, are sealed in a disposable unit. Since these cartridge units are normally employed in very compact copiers with little spare space, units in a copier that consume unduly large amounts of toner are unacceptable because the toner housings must be too large to fit in a compact copier.
Thus, problems encountered with belt-type photoreceptors having a seam include repeated striking of the seam by cleaning blades. This causes toner developer or liquid ink agglomerates to form that are trapped at the irregular surface of the seam. Belted photoreceptors also tend to delaminate at the seam when the seam is subjected to constant battering by the cleaning blade. Plus, collisions between the cleaning blade and seam damage the blade thereby shortening blade and photoreceptor life and degrading copy quality. Also, toner consumption can be to great for some applications.
If a photoreceptor seam is coated with a solution of a resinous coating material dissolved in a suitable solvent and heated or placed in a vacuum to accelerate the removal of the solvent, the incipient photoreceptor seam coating can undergo substantial redistribution and deformation resulting, for example, in non-uniform defects such as creasing, wrinkling, cracking, blisters and the like due to solvent attack of components in the photoreceptor. Moreover, during the use of solution based coating techniques, the solvent can attack one or more layers of the photoreceptor belt and cause significant damage or complete destruction of the functional properties of the photoreceptor belt such as the flexibility, structural strength, or the imaging characteristics of the belt.